Attachment for portable drills

ABSTRACT

A device for applying pressure to a portable power drill for feeding the drill tool into a work piece is formed by a sleeve which can be detachably secured to the steadying handle of the drill. The sleeve is carried between a first pair of parallel lever arms which are mounted between and pivoted to a second pair of longer lever arms having a handle for applying pressure. The sleeve is mounted in apertures, formed in two spaced plates secured to and between the first pair of lever arms, for turning movement about its axis. A work piece embracing chain has one end fastened to the forward end of one of the second pair of arms and the other end adapted to be releaseably held by an upturned hook portion formed on the forward end of the other second arm.

United States Patent Salter [451 Oct. 17, 1972 [541 ATTACHMENT FOR PORTABLE DRILLS [57] ABSTRACT [72] Inventor: Donald G. Salter, Route 1, New

Avon Township, Minn. 56283 [22] Filed: March 16, 1971 [21] Appl. No.: 124,811

[52] U.S. Cl ..408/92 [51 Int. Cl. ..B23b 47/18 [58] Field of Search ..408/92 [56] References Cited UNITED STATES PATENTS Salfer ..408/92 Primary Examiner-Gil Weidenfeld Attorney-G. A. Ellestad A device for applying pressure to a portable power drill for feeding the drill tool into a work piece is formed by a sleeve which can be detachably secured to the steadying handle of the drill. The sleeve is carried between a first pair of parallel lever arms which are mounted between and pivoted to a second pair of longer lever arms having a handle for applying pressure. The sleeve is mounted in apertures, formed in two spaced plates secured to and between the first pair of lever arms, for turning movement about its axis. A work piece embracing chain has one end fastened to the forward end of one of the second pair of arms and the other end adapted to be releaseably held by an upturned hook portion formed on the forward end of the other second arm.

2 Claims, 4 Drawing Figures ATTACHMENT FOR PORTABLE DRILLS BACKGROUND OF THE INVENTION This invention relates to portable power drills and more particularly it has reference to an attachment which can be detachably secured to the drill and is constructed for applying pressure to feed the drill into a work piece. Pressure applied manually to a lever arrangement is transmitted substantially alongthe axis of the drill tool to provide improved efficiency and accuracy'and also lessen the tendency to break drills.

SUMMARY OF THE INVENTION Objects of the invention are to provide a pressure applying attachment for portable power drills which will be simple and rugged in structure, convenient in use and adapted toapply pressure axis of the drill tool.

According to the invention, there is mounted between a first pair of spaced parallel lever arms two spaced plates. Portions of the plates are secured to the respectively adjacent lever arms with one of the plates adjacent to the rear ends of the lever arms. The plates are provided with aligned circular apertures forming bearings within which a cylindrical sleeve is mounted for turning movement about its axis. A second pair of spaced parallel lever arms is positioned with its arms outwardly of and respectively adjacent to the arms of the first pair. The second pair of arms is longer than the first pair of arms and the rear ends of the second pair of arms are connected by a part forming a handle. The forward ends'of the first pair of arms are pivotally connected along a common axis to the respectively adjacent arms of the second pair and with said axis positioned adjacent to the forward ends of the second pair of arms. Adapted to be trained around and in encircling relation to a work piece is a link chain which is attached to the forward end of one of the second pair of arms and adapted to be held in encircling engagement by placing a link on an upturned hook portion formed on the forward end of the other of the second arms. The attachment is secured to a power drill by slipping the steadying handle of the drill into the sleeve and securing it by set screws carried by the sleeve so that the pivot axis of the first pair of arms intersects the axis of the drill. The link chain is then trained around the work piece. Since the sleeve can turn about its axis, pressure applied anywhere along the handle will be transmitted substantially along the axis of the drill.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings:

FIG. 1 is a side elevational view showing the attachment embodying the invention mounted on a drill.

FIG. 2 is a top plan view of the attachment with chain parts broken away.

FIG. 3 is a side elevational view of the same with parts broken away.

FIG. 4 is a sectional view, on an enlarged scale, taken on line 4-4 of FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENTS A preferred embodiment of the invention is shown in the drawings wherein indicates, generally, the pressure applying attachment which in FIG. 1 is shown atsubstantially along the tached to a conventional portable power drill 11. The attachment comprises a first pair of spaced parallel lever arms 12 and 13 between which are mounted two spaced plates 14 and 15 having side portions secured as by welding, to the respectively adjacent lever arms 12 and 13. The two plates are provided, respectively, with aligned circular apertures 16 forming bearing means within which the cylindrical sleeve 17 is mounted to turn about its axis. The plate 14 is secured to the rear end portions of lever arms 12 and 13 to thereby provide with plate 15 a firm mounting for the sleeve 17 on substantially the rear portion the arms 12 and 13.

A second pair of spaced parallel lever arms 18 and '19 is positioned outwardly of and respectively adjacent to the first pair of lever arms 12 and 13 as shown in FIG. 2. The arms 18 and 19 are longer than the arms 12 and 13 and rear ends ofarms l8 and 19 are connected by a part providing a handle such as formed, for example by a bolt 20 passing through a tube 21. The forward ends of the arms 12 and 13 are pivotally mounted on the respectively adjacent arms 18 and 19 by means of bolts 22 and washers 23 to turn about a common axis which is located adjacent to the forward ends of the arms 18 and 19. A link chain 24 which is adapted to encircle a work piece has one end fastened to the forward end of arm 18 so that the chain may snugly engage the work piece by selectively hanging a link on an upturned hook portion 25 formed on the forward end of, arm 19.

In operation, the attachment 10 is mounted on a portable power drill 11 by slipping the sleeve 17 over the steadying handle 26 which projects laterally from the body of drill 11. The sleeve 17 is positioned on the handle 26 so that the turning axis of lever arms 12 and l3 intersects the axis of the drill tool 27. The sleeve 17 is secured in position on the handle 26 by tightening the clamping screws 28 and 29 which are threaded into the respective ends of the sleeve 17. The link chain 24 is then looped around a work piece W and brought into snug engagement therewith by hanging a selected link on the upturned hook 25. Downward pressure applied manually to handle 21 will be transmitted downwardly along the axis of the drill tool 27 to feed it into the work piece W.

Since the sleeve 17 is mounted to turn about its axis, downward pressure applied to any point on the handle 21 will be balanced and transmitted substantially uniformly along the axis of the drill tool 27. Without such structure, unevenly applied pressure would tend to force the drill tool 27 to one side and produce an inaccurate and oversize hole. Such unevenly applied pressures would also tend to cause breakage of drill tools of the smaller diameters. When the drilling operation is completed, raising the handle 21 will lower the forward ends of arms 18 and 19 and cause the link to drop off the hook portion 25 to thereby release the chain 24 from the work piece W. This quick release feature is of great convenience to the operator since it can be accomplished when both hands are occupied with holding and steadying the drill.

Because of its relatively simple structure, the attachment can be readily produced by performing relatively simple mechanical operations upon standard stock material such as steel bars, tubing and other mechanical parts. The mounting of the sleeve 17 within the bearing formed by the spaced plates 14 and 15 located between and secured to the arms 12 and 13 provides a simple yet rugged construction for transmitting the pressure applied to the handle 21. Various modifications may be made without departing from the spirit of the invention as pointed out in the appended claims.

lclaim:

1. An attachment for a portable drill having a laterally projecting steadying handle, said attachment comprising a cylindrical sleeve adapted to slidably receive the handle, means for clamping the handle to the sleeve, a first pair of spaced parallel lever arms, two spaced plates carried between and secured to the respectively adjacent lever arms, said plates having aligned apertures forming bearing means, said sleeve being mounted in the bearing means to turn about its axis, a second pair of spaced parallel lever arms positioned respectively outwardly of and adjacent to the first pair of lever arms, said second pair of arms extending rearwardly beyond the rear end of the sleeve and forwardly beyond the forward ends of the first pair of arms, the rear end portions of the second pair of arms being connected by a part forming a handle, the forward ends of the first pair of arms being pivotally connected to the respectively adjacent second pair of arms along a common axis which is adjacent to the forward ends of the second pair of arms, chain means attached to the forward end of one of the second arms and adapted to be directed around a work piece and selectively secured to the forward end of the other of the second arms whereby pressure applied to the handle will be transmitted substantially along the axis of a tool carried by the drill.

2. The structure recited in claim 1 in which one of the spaced plates is secured to the respectively adjacent rear ends of the first pair of lever arms and the forward end of one of the arms of the second pair of arms has an upturned hook portion for selective engagement with a link of the chain means whereby'upward movement of the handle will release the link from the hook portion and thereby facilitate removal of the chain from the work piece. 

1. An attachment for a portable drill having a laterally projecting steadying handle, said attachment comprising a cylindrical sleeve adapted to slidably receiVe the handle, means for clamping the handle to the sleeve, a first pair of spaced parallel lever arms, two spaced plates carried between and secured to the respectively adjacent lever arms, said plates having aligned apertures forming bearing means, said sleeve being mounted in the bearing means to turn about its axis, a second pair of spaced parallel lever arms positioned respectively outwardly of and adjacent to the first pair of lever arms, said second pair of arms extending rearwardly beyond the rear end of the sleeve and forwardly beyond the forward ends of the first pair of arms, the rear end portions of the second pair of arms being connected by a part forming a handle, the forward ends of the first pair of arms being pivotally connected to the respectively adjacent second pair of arms along a common axis which is adjacent to the forward ends of the second pair of arms, chain means attached to the forward end of one of the second arms and adapted to be directed around a work piece and selectively secured to the forward end of the other of the second arms whereby pressure applied to the handle will be transmitted substantially along the axis of a tool carried by the drill.
 2. The structure recited in claim 1 in which one of the spaced plates is secured to the respectively adjacent rear ends of the first pair of lever arms and the forward end of one of the arms of the second pair of arms has an upturned hook portion for selective engagement with a link of the chain means whereby upward movement of the handle will release the link from the hook portion and thereby facilitate removal of the chain from the work piece. 